Adolescent girls in violent or controlling relationships are likely to be at higher risk for HIV and STIs. Their risk of relationship violence or power imbalances may be greater when the partner is two or more years older. The purpose of this study is to test a proposed model of the correlations between sexual relationship power and intimate partner violence (IPV) and HIV risk related sexual behaviors in a sample of at-risk adolescent girls. The model is derived from Blanc's evidence-based framework for assessing the relationship between gender power relations and reproductive health in populations as risk for power imbalances. Specifically, the study aims to investigate the relationship of sexual partners'age discordance of more than two years to high-risk sexual behavior, in adolescent girls ages 14-18, as well as the mediating role of sexual relationship power and IPV in that relationship. A cross-sectional, descriptive, survey design will be used to evaluate the model of Proposed Predictors of Sexual Risk in Adolescent Girls. Data will be collected from 150 sexually active adolescent girls at an urban school-based health center, in a low-income neighborhood. Data collection will be done via a self-administered, computer-assisted survey, Promote Health, which will analyze responses and format a report with health information, referrals, and resources specific to the individual participant. Data will be analyzed for main effects of demographic variables, including age of adolescent girl, race/ethnicity and acculturation status, and history of physical or sexual abuse. If main effects are determined, then these factors will be controlled for in regression analysis. The role of sexual relationship power and IPV as mediators of the relationship among partner age discordance and high risk sexual behaviors will be determined through multiple regression analysis. Sub-analyses will be conducted to further investigate the correlations among variables, for example sexual relationship power and IPV. The proposed research questions are critical in addressing the needs for early intervention in HIV/STD prevention for adolescent girls, who are at high risk for IPV and one of the fastest growing groups infected with HIV and other STIs. Understanding the prevalence and effects of power imbalances in romantic relationships is essential in developing strategies to reduce HIV, other STIs, and IPV. If relationship factors, such as age discordance, relative power, and violence increase the likelihood of sexual risk behaviors in at-risk adolescent girls, this knowledge can be used to shape questions asked in clinical risk assessment, and to develop prevention interventions and public health policy.